Valve closure system and valve closure assembly having torque limiting

ABSTRACT

A valve closure assembly ( 50 ) for remotely and automatically closing a railway tank car valve (V 1,  V 2,  V 3,  V 4 ), characterized by improved convenience in mounting on a tank car dome ( 160 ) and adaptability to various dome geometries, valve configurations, and car-to-car dimensional variations. A clamp assembly ( 52 ) mounts assembly ( 50 ) on dome ( 160 ). An adapter ( 90 ) operated by a motor ( 58 ) acting through a torque limiter ( 88 ) turns a valve handle (A 1,  A 2,  A 3,  A 4 ) when motor ( 58 ) runs. A positioning mechanism ( 54 ) selectively positions adapter ( 90 ) relative to clamp assembly ( 52 ) to establish a spatial relationship between them for enabling clamp assembly ( 52 ) to be placed at a desired location on the dome wall ( 162 ) and adapter ( 90 ) to engage a valve handle. Positioning mechanism ( 54 ) comprises three degrees of freedom of motion for establishing the spatial relationship of adapter ( 90 ) to clamp assembly ( 52 ), two of which are in the horizontal plane.

REFERENCE TO RELATED APPLICATIONS AND PRIORITY CLAIMS

[0001] This application derives from the following commonly ownedcopending patent applications, the priorities of which are expresslyclaimed: Provisional Application No. 60/374,703, filed on Apr. 22, 2002in the names of Richard Fortino and David N. Maniez Jr. and ProvisionalApplication No. 60/374,653, filed on Apr. 22, 2002 in the names ofRichard Fortino and David N. Maniez Jr.

FIELD OF THE INVENTION

[0002] This invention relates to a valve closure system and valveclosure assembly for promptly and automatically closing tank valves,especially tank valves of railway tank cars. The invention also relatesto methods of making and using the valve closure assembly.

BACKGROUND OF THE INVENTION

[0003] Various fluids are transported by railway tank cars. Such tankcars have domes where various valves are located. The portions of thevalves that are external to the tank, including the valve handles arehoused within a protective housing that has a hinged lid or cover thatis opened to expose the handles. One or more of the valves is openedduring certain procedures involving loading and/or unloading fluid intoand/or from the tank. During such procedures, a valve closure assemblyhaving a power actuator is hoisted onto the dome and mounted there. Thepower actuator is fitted to the handle of the open valve and can beremotely and automatically operated to close the open valve whenconditions call for valve closing.

SUMMARY OF THE INVENTION

[0004] The present invention relates to improvements in valve closureassemblies for remotely and automatically closing an open tank car valvewhen conditions call for valve closing. The inventive valve closureassembly is characterized by improved convenience in mounting and use ona railway tank car and by better adaptability to various types ofprotective housings and various tank car valve configurations within thehousings. It is especially suited for valves that have soft seating. Itis also tolerant of car-to-car variations in standard dimensions thatare promulgated by industry for various valve configurations. Theinventive principles include methods of making and using the valveclosure assembly, and certain aspects of the invention may be useful inother than the context of a railway tank car.

[0005] One generic aspect of the invention relates to an assembly forturning an external handle of a tank dome valve about a vertical axis.The assembly comprises a mounting for removably mounting the assembly ona tank dome and an adapter operated by a motor acting through a torquelimiter for engaging the valve handle and turning the handle when themotor operates the torque limiter. The assembly further comprises apositioning mechanism for selectively positioning the adapter relativeto the mounting to establish a spatial relationship of each to the otherfor enabling the mounting to be placed at a desired location on the domeand the adapter to engage the valve handle. The positioning mechanismcomprises two degrees of freedom of motion in a horizontal plane forestablishing the spatial relationship of the adapter to the mounting inthe horizontal plane.

[0006] Another generic aspect of the invention relates to an assemblyfor turning an external handle of a tank dome valve about a verticalaxis where the assembly comprises a mounting for removably mounting theassembly on a tank dome, an adapter operated by a motor acting through atorque limiter for engaging the valve handle and turning the handle whenthe motor operates the torque limiter, and a positioning mechanism forselectively positioning the adapter relative to the mounting toestablish a spatial relationship of each to the other for enabling themounting to be placed at a desired location on the dome and the adapterto engage the valve handle. The positioning mechanism comprises threedegrees of freedom of motion for establishing the spatial relationshipof the adapter to the mounting.

[0007] Another generic aspect of the invention relates to a method ofassociating a valve operating assembly with a fluid-containing tank forenabling an adapter that is operated by a motor of the valve operatingassembly acting through a torque limiter to turn an external handle of avalve on the tank about an axis of turning while a mounting of theassembly is supporting the assembly on the tank. The method comprisespositioning the mounting relative to the torque limiter and adapter viaa positioning mechanism of the valve operating assembly that has twodegrees of freedom of motion in a plane of reference that isperpendicular to the axis of turning to establish a spatial relationshipfor placing the adapter in engagement with the valve handle and forplacing the mounting at a desired location on the tank.

[0008] Another generic aspect of the invention relates to a method ofassociating a valve operating assembly with a fluid-containing tank forenabling an adapter operated by a motor of the valve operating assemblyacting through a torque limiter to turn a valve on the tank about anaxis of turning while a mounting of the assembly is supporting theassembly on the tank wherein the method comprises positioning themounting relative to the torque limiter and adapter via a positioningmechanism of the valve operating assembly that has three degrees offreedom of motion to establish a spatial relationship for placing theadapter in engagement with the valve handle and for placing the mountingat a desired location on the tank.

[0009] Still another generic aspect of the invention relates to a methodof associating a valve operating assembly comprising a mounting, apositioning mechanism, and an adapter operated by a motor acting througha torque limiter, with a dome of a fluid-containing tank comprising avalve having a handle that is external to the tank and an upright wallspaced horizontally from the valve handle for enabling the adapter toengage the valve handle and turn the handle about an axis of turningwhile the mounting is supporting the assembly at a desired location onthe dome in horizontally spaced relation to the valve handle. The methodcomprises disposing the valve operating assembly vertically over thedome, lowering the assembly onto the dome, and causing the positioningmechanism to relatively position the torque limiter so as to place theadapter in engagement with the valve handle and to relatively positionthe mounting so as to place the mounting at a desired location on theupright wall.

[0010] The foregoing features, advantages, and aspects of the invention,along with additional ones, will be seen in the ensuing description andclaims, which are accompanied by drawings. The drawings disclose apresently preferred embodiment of the invention according to the bestmode contemplated at this time for carrying out the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a perspective view showing a presently preferredembodiment of valve closure system comprising a valve closure assemblyaccording to the present invention.

[0012]FIG. 2 is an exploded perspective view of FIG. 1.

[0013]FIG. 3 is a top of plan view of FIG. 1.

[0014]FIG. 4 is a vertical cross section view in the direction of arrows4-4 in FIG. 3.

[0015]FIG. 5 is a vertical cross section view in the direction of arrows5-5 in FIG. 3.

[0016]FIG. 6 is a vertical cross section view in the direction of arrows6-6 in FIG. 3.

[0017]FIG. 7 is a perspective view of a clamp assembly of the valveclosure assembly.

[0018]FIG. 8 is an elevation view in the direction of arrow 8 in FIG. 7.

[0019]FIG. 9 is a right side elevation view of FIG. 8.

[0020]FIG. 10 is a top view of FIG. 9.

[0021]FIG. 11 is a perspective view of one element of the clamp assemblyby itself.

[0022]FIG. 12 is an elevation view in the direction of arrow 12 in FIG.11.

[0023]FIG. 13 is a right side elevation view of FIG. 12.

[0024]FIG. 14 is a top view of FIG. 12.

[0025]FIG. 15 is a perspective view of another element of the clampassembly by itself.

[0026]FIG. 16 is an elevation view in the direction of arrow 16 in FIG.15.

[0027]FIG. 17 is a right side elevation view of FIG. 16.

[0028]FIG. 18 is a top view of FIG. 16.

[0029]FIG. 19 is a perspective view of still another element of theclamp assembly by itself.

[0030]FIG. 20 is an elevation view in the direction of arrow 20 in FIG.19.

[0031]FIG. 21 is a right side elevation view of FIG. 20.

[0032]FIG. 22 is a top view of FIG. 20.

[0033]FIG. 23 is a perspective view of an element of a motor head of thevalve closure assembly by itself.

[0034]FIG. 24 is an elevation view in the direction of arrow 24 in FIG.23.

[0035]FIG. 25 is a left side elevation view of FIG. 24.

[0036]FIG. 26 is a perspective view of another element of the motor headby itself.

[0037]FIG. 27 is an elevation view in the direction of arrow 27 in FIG.26.

[0038]FIG. 28 is a top view of FIG. 27.

[0039]FIG. 29 is a right side view of FIG. 28.

[0040]FIG. 30 is a perspective view of an element of a head positioningmechanism of the valve closure assembly by itself.

[0041]FIG. 31 is a view in the direction of arrow 31 in FIG. 30.

[0042]FIG. 32 is a bottom view of FIG. 31.

[0043]FIG. 33 is a right side view of FIG. 32.

[0044]FIG. 34 is a perspective view of another element of the motor headby itself.

[0045]FIG. 35 is a view in the direction of arrow 35 in FIG. 34.

[0046]FIG. 36 is a bottom view of FIG. 31.

[0047]FIG. 37 is a cross section view taken in the direction of arrows37-37 in FIG. 35.

[0048]FIG. 38 is a perspective view of the valve closure assemblymounted on a railway tank car.

[0049]FIG. 39 is a top plan view of FIG. 38.

[0050]FIG. 40 is a front elevation view of FIG. 39.

[0051]FIG. 41 is a right side elevation view of FIG. 40.

[0052]FIG. 42 is a perspective view of a direct drive adapter by itself.

[0053]FIG. 43 is a top plan view of FIG. 42.

[0054]FIG. 44 is a vertical cross section view in the direction ofarrows 44-44 in FIG. 43.

[0055]FIG. 45 is a cross section view in the direction of arrows 45-45in FIG. 42.

[0056]FIG. 46 is a perspective view showing a torque limiter suitablefor use in the present invention.

[0057]FIG. 47 is a front elevation view of the torque limiter in thedirection of arrow 47 in FIG. 46.

[0058]FIG. 48 is a bottom plan view in the direction of arrows 48-48 inFIG. 47.

[0059]FIG. 49 is a vertical cross section view in the direction ofarrows 49-49 in FIG. 48.

[0060]FIG. 50 is a horizontal cross section view in the direction ofarrows 50-50 in FIG. 49, but rotated 180° in the plane of the Figure.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0061]FIGS. 1 through 6 illustrate a presently preferred embodiment ofvalve closure assembly 50 of a valve closure system in accordance withprinciples of the invention. The valve closure assembly is adapted formounting on the dome of a railroad tank car and operative coupling witha handle of a valve on the tank car for enabling the valve to beautomatically closed in a situation where immediate valve closure iscalled for.

[0062] The dome of a representative of railroad tank car comprises aprotective housing. The protective housing comprises a circular uprightwall that is supported on a manway cover. The manway cover is supportedon a flange of a circular manway opening in the tank dome. That assemblycarries various valves whose handles are disposed external to the tankinterior, but within the interior of the protective housing. Piping forthe valves extends through the manway cover into the tank interior. Theopen top of the circular upright wall of the protective housing isclosed by a circular cover that can be opened to provide access to theinterior of the protective housing, and hence to the valve handles. Withthe cover open, the rim of the circular wall is exposed.

[0063] The present invention utilizes the exposed rim of the circularwall of the protective housing for securely mounting valve closureassembly 50 on a tank car dome. Valve closure assembly 50 comprises aclamp assembly 52 for clamping on the rim of the circular wall of theprotective housing, a positioning mechanism 54 that is supported on theclamp assembly, and a motor head 56 that is positioned by thepositioning mechanism for operative association with a valve handle thatwill enable system 50 to promptly close the associated valve by turningthe valve handle when called upon to do so.

[0064] Motor head 56 comprises a motor 58, preferably an air motor, thatis mounted upright on a motor mounting 60. Mounting 60 comprises a baseplate 62 that is shown by itself in detail in FIGS. 26 through 29.Mounting 60 is securely fastened to positioning mechanism 54 through arectangular tie bar 64 using screws 66. A bracket 68 is fastened byfastening elements 70, 72 to base plate 62. A handle 74 is in turnfastened to bracket 68 by fasteners 76. Handle 74 comprises a handlebar78 and a grip 80.

[0065] From this description it can be appreciated that mounting 60comprises a horizontal platform on which motor 58 is securely mountedand a vertical wall that extends upward from that platform along sidethe motor. The horizontal portion of base plate 62 forms the horizontalplatform of mounting 60, and the vertical portion of base plate 62 andbracket 68 together form the vertical wall of the mounting. Handle 74extends horizontally away from the side of that vertical wall oppositemotor 58 near the upper end of the motor.

[0066] The shank of a respective headed screw 81 passes through each ofsix holes 83 in base plate 62 to thread into a respective threaded holein an end of the air motor body. Tightening of the screws secures motor58 on motor mounting 60. It is considered desirable to protectivelyenclose motor 58 by a circular cylindrical shield 82. A circular ring 84is disposed around the air motor body at one end and clamped to the airmotor body using three set screws 85 that are threaded into tappedthrough-holes in ring 84. One end of shield 82 fits over ring 84 toestablish concentricity of the shield to the motor body and containsseveral clearance holes that allow the shanks of headed screws 87 topass through and thread into tapped holes in ring 84. These screws aretightened to secure the shield to the ring. An annular ring seal 86closes the annular space between the shield and the motor body at theopposite end. The horizontal platform that base plate 62 provides tosupport motor 58 comprises a central through-hole 89 surrounded by thesix holes 83. Through-hole 89 allows the motor shaft 91 to pass downwardthrough the horizontal platform where an input of a torque limiter 88 iscoupled to the shaft using a hitch pin 93. An adapter 90 is in turnfastened to the output of torque limiter 88 using screws 95. The upperend of motor 58 remains exposed to provide for connection of an air line(not shown) to the motor.

[0067] Positioning mechanism 54 comprises circular cylindrical rods 92,94, linear bearings 96, 98, and a pillow block 100. Rods 92, 94 aredisposed horizontally spaced apart in mutually parallel relationship.Tie bar 64 at one end of rods 92, 94 and a second tie bar 102 at theopposite ends of the rods have counterbored through-holes that allow therod ends to fit with precision to the counterbores of the tie bars.Screws 66 pass through the clearance holes 103 of one of four pairs ofsuch clearance holes in base plate 62 to enter the through-holes in tiebar 64 and thread into tapped holes in the rods. The uppermost pair ofholes 103 are used for fastening bracket 68 to base plate 62, while theother three pairs provides for motor head 56 to be fastened topositioning mechanism 54 at any of three different elevations. Rods 92,94 have tapped holes at their opposite ends, which seat with precisionin the counterbores in the through-holes in tie bar 102. Screws 104fasten tie bar 102 and the rods together at that end in the same way sothat the assembly of the two tie bars and the two rods forms a part ofthe positioning mechanism that can translate horizontally relative topillow block 100.

[0068] Detail of pillow block 100 is shown in FIGS. 30-33. Linearbearings 96, 98 are fit to respective through-holes 106, 108 in pillowblock 100. Rods 92, 94 pass through these linear bearings. Midwaybetween and at a right angle to through-holes 106,108, pillow block 100comprises a vertical through-hole 110. A linear bearing 112 is fit tothrough-hole 110. A circular rod 114 that has tapped holes at oppositeends passes through linear bearing 112. A stop disk 116 is fastened tothe upper end of rod 114 using a screw 118. A screw 120 fastens clampassembly 52 to the lower end of rod 114.

[0069] During the process of assembling positioning mechanism, tubularbumpers 121 are fit onto ends of rods 92, 94 proximate each tie bar 64,102. Bumpers 121 limit the travel of pillow block 100 on rods 92, 94 sothat the pillow block cannot strike either tie bar. The lengths of thebumpers are chosen to also provide sufficient clearance between thepillow block and the tie bars at the limits of pillow block travel sothat pinch points are not present between the pillow block and the tierods at the limits of pillow block travel.

[0070] FIGS. 7-22 show that clamp assembly 52 comprises a bracketassembly 122 fabricated from two base clamp parts 124, 126 and astrengthener plate 128. In addition to bracket assembly 122, clampassembly 52 comprises a hand screw 130 that can be manually turned by aturning knob 159 shown in FIGS. 1-4 and 6.

[0071] Part 126 is shaped to fit onto the rim of the protective housingof a railway tank car and comprises spaced apart vertical side walls132, 134 that are joined by a horizontal top wall 136, endowing the partwith an inverted U-shape as shown by FIG. 17. When the part is fit ontothe protective housing rim, wall 132 is disposed inside the rim, wall134 is disposed outside the rim, and top wall 136 rests on the top edgesurface of the rim. Hence walls 132, 134 are spaced apart a distancethat is greater than the thickness of the protective housing rim.

[0072] Part 124 is shaped to nest on part 126 and comprises a horizontalrectangular top wall 138 and legs 140, 142, 144, 146 depending from thefour corners of top wall 138. In the direction of the thickness of theprotective housing rim, part 124 is longer than part 126, but part 124is shorter than part 126 in a direction at 900 to the thickness of theprotective housing rim. Between leg 140 and leg 142, part 124 has adownwardly open rectangular throat. A like throat exists between leg 144and leg 146. The two throats are dimensioned so that part 124 fitssnuggly onto part 126, as shown in FIGS. 7 and 9.

[0073] Strengthener plate 128 is rectangular in shape and is disposedagainst the outer surface of side wall 134 and between the lower ends oflegs 142, 146. The three parts 124, 126, 128 are aluminum alloy and arejoined together by any suitable metallurgical joining technique to formbracket assembly 122.

[0074] Top wall 138 has a circular hole 150 at its center that allowsthe lower end of rod 114 to pass through and abut top wall 136. Thelatter wall has a countersunk hole 152 for allowing the flat head ofscrew 120 to seat flush in the countersink. Because the two walls 136,138 are spaced vertically apart and rod 114 has a close fit to hole 150,rod 114 is rigidly supported on clamp assembly 52. Rigidity may beenhanced by joining rod 114 to wall 138.

[0075] Strengthener plate 128 comprises a tapped hole 154 into which thethreaded shank 156 of hand screw 130 is threaded. Side wall 134 may havea clearance hole 157 for shank 156, or it may provide an extension ofthe tapped hole in plate 128. Although the thickness of wall 134 may besufficient for the forces that it will experience during use of thevalve closure system, that thickness may be insufficient to provide thedesired length for the tapped hole needed for hand screw 130.Strengthener plate 128 is therefore included to provide the desiredtapped hole length into which shank 156 is threaded.

[0076] FIGS. 38-41 illustrate an example of how valve closure assembly50 is used on a railway tank car. The tank car has a centrally locateddome that has a protective housing 160. The protective housing comprisesa circular upright side wall 162 on which a top cover (not shown) ishinged for opening and closing the housing. Side wall 162 is supportedon a manway cover 164 that is part of an assembly that carries fourvalves V1, V2, V3, V4 in this example. The valves comprise respectivehandles A1, A2, A3, A4 that are disposed external to the tank interior,but within the interior of housing 160. With the top cover swung open,the rim of side wall 162 is exposed.

[0077] One or more of the valves is (are) opened, as appropriate to theparticular procedure being performed on the tank car. A valve closureassembly 50 can be associated with the handle of any opened valve. Theefficient geometry of valve closure assembly 50 allows multiple valveclosure assemblies to be used concurrently. In this way a respectiveindividual valve closure assembly 50 can be associated with a respectivehandle so that if all four valves are opened, they can be automaticallyclosed by the respective valve closure assembly. The example shown inFIGS. 38-41 involves only a single valve closure assembly.

[0078] With hand screw 130 backed off sufficiently to provide aclearance from the distal end of shank 156 to side wall 132 of clampassembly 52 that is sufficiently greater than the thickness of the rimof protective housing side wall 162, handle 74 can be grasped toposition the valve closure assembly over protective housing 160 withbracket assembly 122 positioned over the housing side wall rim and thedownwardly open throat of the bracket assembly aligned with the rim andwith motor head 56 positioned over valve V1 and adapter 90 aligned withhandle A1. The valve closure assembly is then lowered until top wall 136of bracket assembly 122 comes to rest on the top edge surface of thehousing side wall rim and adapter 90 comes into engagement with handleA1. Turning knob 159 of hand screw 130 is then grasped and turned toadvance shank 156 against the outside of the housing rim thereby lockingclamp assembly 52 to the protective cover. Other apparatus of the valveclosure system that is not shown in the drawings is able to operatemotor 58 when handle A1 is to be operated to close valve VI. Duringmounting of assembly 50 on a tank car, the linear bearings facilitatethe ability of positioning mechanism 54 to achieve the desiredpositioning of motor head 56 relative to clamp assembly 52. They alsofacilitate any movement that may occur when motor 58 is operated, suchas vertical motion arising from valve handle travel as the valve handleis turning. The linear bearings are commercially available products thatincorporate circulating balls. Assembly 50 also adapts to a range ofvariations in valve location, a range in departure of a valve axis fromvertical, and a range of thickness of the protective housing rim,without compromising the ability of the assembly to close an open valve.

[0079] Handle A1 has a shape that accepts the generally square shape ofadapter 90 in a manner that allows the outer non-circular edge surfaceof the adapter to turn the handle. As motor 58 operates to turn thehandle, the handle may or may not translate vertically as it is turning.The range of vertical travel of pillow block 100 on rod 114 and a propervertical setting of motor head 56 on tie rod 64 will enable the motorhead to travel vertically with the valve handle so that the drivingrelation of the adapter to the handle is maintained until the valve isfully closed.

[0080] Certain valves have “hard” seats while others have “soft” seats.Torque that is applied to close a valve that has a soft seat should notexceed a predetermined torque. Torque limiter 88 is therefore used inconjunction with valves that have soft seats to provide a low-torquedrive. Where a valve has a hard seat, torque limiter 88 is disconnectedfrom motor shaft 91 by extracting hitch pin 93 and lowering the torquelimiter to disengage its input from the motor shaft. A direct driveadapter assembly is then connected to the motor shaft.

[0081] FIGS. 42-45 show one example of such a direct drive adapter 180.It comprises a cylindrical hub 182 with a square drive hole 184 forfitting onto motor shaft 91. A transverse hole 186 is arranged forregistration with a hole in the motor shaft so that hitch pin 93 canpass through both holes to pin the adapter to the motor shaft. A baseplate 188 at the end of hub 182 carries two drive pins 190 on the faceof the base plate that is opposite hub 182. Drive pins 190 are arrangedin a geometric pattern that allows them to fit into diametricallyopposite holes 192 in the handles A2, A3, A4, of the other valves V2,V3, V4 in FIGS. 39 and 40 when assembly 50 is associated with one ofthem.

[0082] FIGS. 46-50 illustrate detail of torque limiter 88. The input oftorque limiter 88 comprises an input member 190, and the output, anoutput member 192. Input member 190 comprises a cylindrical shaft 194that is concentric with a vertical axis of rotation 196. Intermediateopposite ends of shaft 194, input member 190 comprises a circular flange198. Output member 192 comprises an upwardly open cylindrical cup thatis concentric with axis 196 and has a circular bottom wall 200 and acircular cylindrical side wall 202 extending vertically from bottom wall200.

[0083] A lower portion of input member 190 that includes flange 198 isdisposed within the interior of output member 192. A circular annularcover member 204 closes the open upper end of output member 192 justabove flange 198 to capture input member 190 on output member 192. Theouter margin of cover member 204 seats on an internal shoulder 206 inwall 202, and the cover member is retained by a retainer (not shown)that seats in a groove 208 that is present in wall 202 above shoulder206 at a distance just greater than the thickness of cover member 204.

[0084] The face of bottom wall 200 that is toward the interior of outputmember 192 provides a mounting for a bearing assembly 210, and the lowerface of cover member 204 provides a mounting for another bearingassembly 212. The bearing assemblies are concentric with axis 196 andprovide a journal between the input and output members that allows themto turn relative to each other for torque limiting, as will become moreapparent from further description.

[0085] A torque responsive mechanism 214 (shown in FIG. 50) is presentwithin the interior of the torque limiter between cover member 204 andbottom wall 200 and in surrounding relationship to shaft 194. Themechanism comprises a pawl 216, two compression springs 218, 220, andthree spring compressors 222, 224, 226.

[0086] Each spring compressor 222, 224, 226 has a radially inner facethat is concave toward the outer surface of shaft 194, a radially outerface that is convex toward the inner surface of side wall 202, a flatupper end face that confronts the lower face of flange 198, and a flatlower end face that confronts the upper face of bottom wall 200surrounding bearing assembly 210. Each spring compressor 222, 224, 226spans a certain number of degrees about axis 196, having vertical sidefaces that are disposed substantially in planes that pass through axis196. One end of spring 218 seats in the vertical side face of springcompressor 222 that is toward spring compressor 224 while the oppositeend of spring 218 seats in the vertical side face of spring compressor224 that is toward spring compressor 222. One end of spring 220 seats inthe vertical side face of spring compressor 224 that is toward springcompressor 226 while the opposite end of spring 220 seats in thevertical side face of spring compressor 226 that is toward springcompressor 224.

[0087] Pawl 216 is carried by input member 190, being pinned to flange198 to pivot about an axis 228 that is parallel to and spaced from axis196. Pawl 216 has a generally rectangular shape and interacts withoutput member 192 and spring compressors 222, 226 to connect anddisconnect input member 190 to and from output member 192 depending onthe torque load that is being imposed on output member 192. When theload is equal to or less than the maximum torque limit of torque limiter88, a radially outer rounded edge 230 of pawl 216 that is parallel withaxis 228 rides in a groove 232 in the inner surface of side wall 202that is parallel with axis 196. The solid line position of pawl 216shown in FIG. 50 is representative. When the load is greater than themaximum torque limit of torque limiter 88, pawl 216 has pivotedsufficiently about axis 228 to swing edge 230 out of groove 232, therebydisconnecting input member 190 from driving output member 192. Thephantom line position of pawl 216 shown in FIG. 50 is representative ofthis condition.

[0088] When pawl 216 is fully radial to axis 194 as shown by the solidline position in FIG. 50, the vertical side faces of spring compressors222, 226 are abutting opposite side faces of pawl 216, although it is tobe appreciated that FIG. 50 doesn't specifically show that. Rather, FIG.50 shows a condition where the turning of pawl 216 about axis 228 to thephantom line position has pushed spring compressors 222, 226 away fromeach other. That pushing has further compressed springs 218, 220 fromthe compression that they had when pawl 216 was fully radial to axis 194and they were flat against opposite side faces of pawl 216.

[0089] With this background description of torque responsive mechanism214, it can be appreciated that with input member 190 being turned toturn output member 192, a condition where there is no load torque on thelatter member will cause pawl 216 to assume substantially the solid linecondition shown in FIG. 50. As the torque load increases, output member192 begins to pivot pawl 216. As pawl 216 pivots, its edge 230 willremain in groove 232 to keep input member 190 driving output member 192until the torque load exceeds the maximum, at which point the pawl willhave pivoted sufficiently to lose driving engagement with groove 232. Asthe pawl is pivoting, it is also forcing the confronting side faces ofspring compressors 222, 226 farther apart, increasingly compressingsprings 218, 220 in the process. Hence, the spring rates of the twosprings in conjunction with the geometry of pawl and groove areinstrumental in setting the maximum torque limit.

[0090] When the load torque returns below the maximum limit, the springforces being exerted through spring compressors 222, 226 on pawl 216will turn the pawl about axis 228 so that edge 230 can re-lodge ingroove 232 when the edge arrives at the groove as the input membercontinues to rotate.

[0091] With torque limiter 88 attached to an air motor to close a softseat valve, the torque limiter will prevent torques that are larger thanthe maximum torque limit from being applied to the valve handle, evenwhen the motor is capable of delivering much greater torque. In thatway, the same valve closure assembly can be used to close both hard andsoft seat tank valves. When the valve closure assembly is mounted on atank for closing a soft seat valve, the motor shaft is pinned to thetorque limiter input, and an adapter that is fastened to the torquelimiter output engages the valve handle. A known air motor has a shaftof square cross section that has a transverse through-hole of circularcross section. The portion of shaft 194 that protrudes upward from covermember 204 has a square drive hole 234 centered on axis 196. Atransverse through-hole 236 passes through shaft 194, intersecting drivehole 234. Torque limiter 88 is coupled to the air motor shaft by fittingthe motor shaft into hole 234 until its transverse through hole alignswith through-hole 236. A hitch pin (not shown) is then passed throughthe aligned holes. Use of a hitch pin for making the connection avoidsthe need to use a tool, an advantage in many situations involvingrailway tank cars.

[0092] For attaching certain adapters for closing certain soft seatvalves to output member 192, a series of six tapped holes 238 equallyspaced around the outer margin of bottom wall 200 are present. Each ofthose adapters has a similar through-hole pattern. When a face of suchan adapter member is placed against wall 200 and the respective holepatterns are registered, the shanks of headed screws are passed throughthe adapter member through-holes and threaded into holes 238 andtightened. Such adapters cannot be coupled and pinned directly to thesquare motor shaft, and so they cannot be used to close a valve withoutthe use of the torque limiter.

[0093] In addition to soft seat adapter 90, further examples of suchadapters are disclosed in commonly owned, non-provisional patentapplication of the same inventors, “Adapters And Adapter Systems ForValve Closure Systems And Valve Closure Assemblies”, Ser. No. ______, ofeven date, (Attorney Docket PowellUS09).

[0094] An adapter for closing a hard seat valve, such as adapter 180,has a square drive hole that allows it to be fit over and pinneddirectly to the motor shaft. It will fit to the handles of certain hardseat tank valves, but not to the handles of certain soft seat tankvalves. The input of the torque limiter has a similar configuration thatallows it to be pinned directly to the motor shaft, but the adaptersthat are used with it have configurations that preclude that possibilitybecause they can attach only to the output of the torque limiter. Thesediverse means of attachment preclude the possibilities that for theparticular valves involved, the torque limiter will be used to close ahard seat valve and that a soft seat valve will be closed without atorque limiter.

[0095] Further examples of adapters for closing various hard seat valvesare also disclosed in the above-referenced patent application of evendate.

[0096] Because positioning mechanism 54 also endows the valve closureassembly with the ability to position motor head 56 at varioushorizontal distances from vertical rod 114, it becomes possible to mountclamp assembly 52 within a range of locations around the rim of theprotective housing with respect to a particular valve. This can be anaid to mounting of a valve closure assembly, particularly when multiplevalve closure assemblies are used on a single tank car.

[0097] Positioning mechanism 54 is therefore capable of selectivelypositioning torque limiter 88 and adapter 90 relative to the clampassembly 52 to establish a spatial relationship of each to the other forenabling the clamp assembly to be placed at a desired location on domewall 162 and the adapter to engage a valve handle. Positioning mechanism54 comprises three degrees of freedom of motion for establishing thespatial relationship of the adapter to the mounting of assembly 50 onwall 162 that is provided by clamp assembly 52.

[0098] Two of those degrees of freedom of motion are in a horizontalplane of reference. They are provided as circular along a horizontal arcby the ability of pillow block 100 to turn on rod 114 about the verticalrod axis and as linear translation of rods 92 horizontally on pillowblock 100. The third degree of freedom of motion is provided by theability of pillow block 100 to travel vertically on rod 114.

[0099] Overall weight is reduced by using aluminum as the material of anumber of the individual parts, such as clamp parts 124, 126, 128 andmotor mount parts 62, 68. An optional trapezoidal hole 170 in theupwardly pointing tongue of bracket 68 lightens its weight. Certainindividuals will be able to carry a valve closure assembly 50 bygrasping handle 74, and able to install it on a tank car without help. Ahole 172 near the tip end of the tongue of bracket 68 is available forattachment of an end of a lift or winch cable that can be used as an aidin lifting the valve closure assembly. Rectangular holes in side walls132, 134 of bracket part 126 can lighten its weight.

[0100] While a presently preferred embodiment of the invention has beenillustrated and described, it should be appreciated that principles ofthe invention are applicable to all embodiments that fall within thescope of the claims that follow hereinafter.

What is claimed is:
 1. An assembly for turning an external handle of atank dome valve about a vertical axis, the assembly comprising: amounting for removably mounting the assembly on a tank dome, an adapteroperated by a motor acting through a torque limiter for engaging thevalve handle and turning the handle when the motor operates the torquelimiter, and a positioning mechanism for selectively positioning theadapter relative to the mounting to establish a spatial relationship ofeach to the other for enabling the mounting to be placed at a desiredlocation on the dome and the adapter to engage the valve handle, whereinthe positioning mechanism comprises two degrees of freedom of motion ina horizontal plane for establishing the spatial relationship of theadapter to the mounting in the horizontal plane.
 2. An assembly as setforth in claim 1 in which the mounting comprises a clamping mechanismfor fitting and clamping onto a rim of an upright wall of the domebounding a zone of the dome containing the valve.
 3. An assembly as setforth in claim 2 in which the positioning mechanism comprises a firstpart supported on the clamping mechanism and a second part thatcomprises an association with the first part for providing thepositioning mechanism with a first of the two degrees of freedom ofmotion that extends along a circular arc centered on the first part. 4.An assembly as set forth in claim 3 in which the first part comprises anupright post on the clamping mechanism and the association of the secondpart with the first part comprises a joint that allows the second partto turn on the post about a vertical axis of the post for causing thefirst degree of freedom of motion to extend along a horizontal circulararc centered on the vertical axis.
 5. An assembly as set forth in claim4 in which the joint comprises a linear bearing between the post and thesecond part to allow the second part not only to turn on the post aboutthe vertical axis of the post but also to be positioned vertically alongthe post.
 6. An assembly as set forth in claim 5 in which thepositioning mechanism further comprises a third part that comprises anassociation with the second part for providing the positioning mechanismwith a second of the two degrees of freedom of motion.
 7. An assembly asset forth in claim 6 in which the association of the third part with thesecond part comprises a joint through which the third part is supportedon the second part and which provides for selective positioning of thethird part relative to the second part along a horizontal linear axis.8. An assembly as set forth in claim 7 in which the second partcomprises a central zone having a vertical through-hole in which thebearing is disposed and zones at either lateral side of the central zoneeach having a respective horizontal through-hole containing a respectivelinear bearing, and the third part comprises rods received in the linearbearings in the horizontal through-holes.
 9. An assembly as set forth inclaim 8 in which the motor is mounted on a horizontal platform of abracket that is attached to a bar that ties together ends of portions ofthe rods that extend from one longitudinal end of the second part, thebracket comprises a vertical wall extending upright from the platformand disposed between the motor and the second part, and the assemblyfurther includes a handle for lifting the assembly attached to thevertical wall in vertically spaced relation to the horizontal platformand extending transversely of the vertical wall in a direction away fromthe motor.
 10. An assembly as set forth in claim 9 in which the motorcomprises an air motor having an output shaft that turns about avertical axis and that protrudes through an aperture in the horizontalplatform to extend below the horizontal platform, and the torque limiterattaches to the output shaft below the horizontal platform.
 11. Anassembly as set forth in claim 9 including another bar that tiestogether ends of portions of the rods that extend from a longitudinalend of the second part opposite the one longitudinal end, and bumpersdisposed between each bar and the second part for preventing either barfrom hitting the second part.
 12. An assembly as set forth in claim 3 inwhich the positioning mechanism further comprises a third part thatcomprises an association with the second part for providing thepositioning mechanism with a second of the two degrees of freedom ofmotion, and the association of the third part with the second partcomprises a joint through which the third part is supported on thesecond part and which provides for selective positioning of the thirdpart relative to the second part along a horizontal linear axis.
 13. Anassembly as set forth in claim 1 in which the positioning mechanismcomprises a first part supported on the mounting, a second part thatcomprises an association with the first part for providing thepositioning mechanism with a first of the two degrees of freedom ofmotion, and a third part that comprises an association with the secondpart for providing the positioning mechanism with a second of the twodegrees of freedom of motion.
 14. An assembly as set forth in claim 13in which the association of the second part with the first partcomprises a joint that allows the second part to be selectivelypositioned on the first part along a circular arc centered on the firstpart.
 15. An assembly as set forth in claim 14 in which the joint thatallows the second part to be selectively positioned on the first partalong a circular arc centered on the first part comprises a joint thatallows the second part to be selectively positioned on the first partalong a horizontal circular arc centered on the first part.
 16. Anassembly as set forth in claim 15 in which the association of the thirdpart with the second part comprises a joint through which the third partis supported on the second part and which provides for selectivepositioning of the third part relative to the second part along a linearaxis.
 17. An assembly as set forth in claim 16 in which the first partcomprises an upright post on the mounting, and the joint that allows thesecond part to be selectively positioned on the first part along ahorizontal circular arc comprises a joint that allows the second partboth to turn on the post as it is selectively positioned along thecircular horizontal arc centered on the vertical axis and also to bepositioned vertically along the post.
 18. An assembly as set forth inclaim 13 in which the association of the third part with the second partcomprises a joint through which the third part is supported on thesecond part and which provides for selective positioning of the thirdpart relative to the second part along a linear axis.
 19. An assembly asset forth in claim 18 in which the joint through which the third part issupported on the second part and which provides for selectivepositioning of the third part relative to the second part along a linearaxis comprises a joint that provides for selective positioning of thethird part relative to the second part along a horizontal linear axis.20. An assembly as set forth in claim 1 in which one of the degrees offreedom of motion describes a circular arc in the horizontal plane andthe other of the degrees of freedom of motion describes a straight linein the horizontal plane.
 21. An assembly for turning an external handleof a tank dome valve about a vertical axis, the assembly comprising: amounting for removably mounting the assembly on a tank dome, an adapteroperated by a motor acting through a torque limiter for engaging thevalve handle and turning the handle when the motor operates the torquelimiter, and a positioning mechanism for selectively positioning theadapter relative to the mounting to establish a spatial relationship ofeach to the other for enabling the mounting to be placed at a desiredlocation on the dome and the adapter to engage the valve handle, whereinthe positioning mechanism comprises three degrees of freedom of motionfor establishing the spatial relationship of the adapter to themounting.
 22. An assembly as set forth in claim 21 in which two of thethree degrees of freedom of motion establish that portion of the spatialrelationship within a plane of reference, and the third degree offreedom of motion establishes that portion of the spatial relationshiptransverse to the plane of reference.
 23. An assembly as set forth inclaim 22 in which the plane of reference is a horizontal plane.
 24. Anassembly as set forth in claim 21 in which two of the three degrees offreedom of motion are along non-parallel straight lines, and the thirddegree of freedom of motion is along a circular arc.
 25. An assembly asset forth in claim 24 in which one of the straight lines is vertical,and the other, horizontal.
 26. An assembly as set forth in claim 24 inwhich the circular arc is centered on a vertical axis.
 27. A method ofassociating a valve operating assembly with a fluid-containing tank forenabling an adapter that is operated by a motor of the valve operatingassembly acting through a torque limiter to turn an external handle of avalve on the tank about an axis of turning while a mounting of theassembly is supporting the assembly on the tank, the method comprising:positioning the mounting relative to the torque limiter and adapter viaa positioning mechanism of the valve operating assembly that has twodegrees of freedom of motion in a plane of reference that isperpendicular to the axis of turning to establish a spatial relationshipfor placing the adapter in engagement with the valve handle and forplacing the mounting at a desired location on the tank.
 28. A method asset forth in claim 27 in which the positioning step comprises relativelypositioning the mounting and the adapter via the positioning mechanismin a plane of reference that is horizontal.
 29. A method of associatinga valve operating assembly with a fluid-containing tank for enabling anadapter operated by a motor of the valve operating assembly actingthrough a torque limiter to turn a valve on the tank about an axis ofturning while a mounting of the assembly is supporting the assembly onthe tank, the method comprising: positioning the mounting relative tothe torque limiter and adapter via a positioning mechanism of the valveoperating assembly that has three degrees of freedom of motion toestablish a spatial relationship for placing the adapter in engagementwith the valve handle and for placing the mounting at a desired locationon the tank.
 30. A method of associating a valve operating assemblycomprising a mounting, a positioning mechanism, and an adapter operatedby a motor acting through a torque limiter, with a dome of afluid-containing tank comprising a valve having a handle that isexternal to the tank and an upright wall spaced horizontally from thevalve handle for enabling the adapter to engage the valve handle andturn the handle about an axis of turning while the mounting issupporting the assembly at a desired location on the dome inhorizontally spaced relation to the valve handle, the method comprising:disposing the valve operating assembly vertically over the dome,lowering the assembly onto the dome, and causing the positioningmechanism to relatively position the torque limiter so as to place theadapter in engagement with the valve handle and to relatively positionthe mounting so as to place the mounting at a desired location on theupright wall.